One common means for providing a lateral branch in a piping system is to cut the main pipe, and then to thread the cut ends. The threaded cut ends of the main pipe are then threaded into a fitting providing a threaded lateral branch, which is usually arranged perpendicular to the axis of the main pipe. A branch pipe is then threaded into a branch of the fitting.
Not only is this a time consuming and labor intensive operation, but also, the provision of a tee branch in an existing piping system further requires that compression unions be provided between both cut ends of the main pipe and the tee fitting, it being difficult or impossible to thread the cut ends of the main pipe into the fitting.
Another common way of providing a branch connection is through the use of a saddle. The saddle is provided with an outlet or hole which is placed in alignment with a similarly sized hole in the surface of the pipe. A clamp or strap, passing around the pipe, holds the saddle firmly in position. A suitable seal is located between the saddle and the pipe so as to completely surround the common aperture between the pipe and saddle. The outlet side of the saddle is provided with a means, such as threading, for the attachment of a pipe or other plumbing appurtenance.
It has been proposed, for example, in British Pat. No. 268,923, issued Apr. 14, 1927 to provide a mechanical tee that does not require the cutting and threading of the main pipe. Instead, a hole is bored laterally through the wall of the main pipe, and a lateral connection to the main pipe is made by threading or otherwise securing a branch pipe within the bored hole. This operation, however, requires that an effective and reliable seal be made between the branch pipe and the outer surface of the main pipe.
According to this prior proposal, this is accomplished by providing a collar which is secured on the branch pipe, and which is moved towards the main pipe by a nut threaded on the branch pipe. The collar is employed to confine and compress an elastomeric seal into sealing engagement with the branch pipe, and into sealing engagement with the outer surface of the main pipe. The free edge of the collar is appropriately pre-formed for it to contact or lie closely proximate to the outer surface of the main pipe.
Prior proposed seals for this purpose, as taught in the said prior British patent, have been provided with dual sealing lips, one being substantially cylindrial and being for sealing engagement with the branch pipe, and the other being closely contoured for it to engage the curved outer surface of the main pipe in continuous sealing engagement therewith in a continuous circular zone surrounding the branch pipe.
In constructions of this type, not only must the free edge of the collar be appropriately pre-formed for it to closely contact the outer surface of the main pipe throughout the entire free edge of the collar, but also, the elastomeric seal must be similarly contoured. Otherwise, either uneven or insufficient pressure will be exerted by the collar on the elastomeric seal to cause it to seat properly on the outer surface of the main pipe, or, the elastomeric seal will be overly compressed and distorted by the collar, with consequential cockling of the sealing lips and defective sealing thereby.
Additionally, any deviation of the main pipe from truly round and cylindrical, or any deviation of the diameter of the main pipe from optimum will result in gapping between the free edge of the collar and the main pipe. If such gapping occurs, extrusion of the elastomeric seal can ensue at the gaps, or, the seal can become entrapped between the free edge of the collar and the main pipe, with resultant cutting of the elastomeric seal and also resulting in a defective seal.
A particular disadvantage to the above methods for making piping branch connections and branching appurtenances, is that a specific and singular configuration is required for every size combination of main pipe and branch size. This results in the necessity to provide enormous inventories encompassing the very large number of commonly required combinations of branch pipe size and main pipe size.